[willamette-fcst] Silverton Hills Midday Forecast_Pete.doc

[Willamette Valley Field Burning Forecast]

SILVERTON HILLS FIELD BURNING FORECAST

OREGON DEPARTMENT OF FORESTRY WEATHER OFFICE

11:45 AM PDT MON JUL 11, 2016



BURN ADVISORY:



Recommended times for agricultural burning are from now until 7 p.m.



Prep burning is not allowed.



WEATHER DISCUSSION:



An unseasonably strong upper-level trough produced more than one-half inch of rain over the weekend, in the Silverton Hills, leaving fields too wet for burning today.  A minor upper-level ridge will bring some clearing this afternoon, but light winds and below-average temperatures will slow down the drying process.



TODAY'S FORECAST:



Becoming partly cloudy this afternoon.



Salem's high temperature today will be near 76°F (average is 81°F).

Relative humidity:  Dropping to near 40% by 5 p.m.

Surface winds: N 3-6 mph; becoming NW 5-10 mph later this afternoon.

Transport winds: NNW 5 mph; becoming NW 5-10 mph later this afternoon.

Mixing height: Rising to 6000 feet by 5 p.m.

Salem's sunset tonight: 8:58 p.m.



(Salem Airport data for Sunday, July 10th: High 70°F; Rainfall: .18")

(Salem Airport rainfall since last Thursday: .45")

(Maximum Ventilation Index expected today: 60)



EXTENDED DISCUSSION:



A weak cold front will likely bring more showers on Tuesday with rainfall totals expected to be near a tenth of an inch.  The rest of the week looks dry with mostly sunny afternoons.  However, temperatures will struggle to get back to near average with continued onshore flow.  Good afternoon mixing and NW transport winds may provide burning opportunities for any dry fields.



Another cool upper-level trough will renew the threat of showers from late Friday through this coming weekend but should not be nearly as potent as its predecessor.  Rainfall totals are expected to be around one-tenth of an inch, with temperatures dropping back to about 10 degrees below average.



The National Weather Service's digital forecast is available at:

http://forecast.weather.gov/MapClick.php?lat=44.90549606158295&lon=-122.8106689453125&site=pqr&unit=0&lg=en&FcstType=text



Notes:



     1.  Mixing height, as used here, is the lowest height at which the

         potential temperature exceeds the potential temperature at the

         surface.  As a practical matter it is the approximate height to

         which a smoke plume will rise assuming good ignition, dry fuels,

         and winds less than about 15 mph.



     2.  Transport winds are a layer average through the mixing height,

         weighted slightly toward the winds at the top of the layer.



     3.  Ventilation Index is the height of the mixing layer (ft) times

         the transport wind speed (mph) divided by 1000.



     4.  Surface wind direction is the general expected wind direction.

         At a specific point surface winds are highly dependent on local

         terrain conditions.



This forecast is provided under an agreement between the Oregon Department

of Agriculture (ODA) and the Oregon Department of Forestry (ODF).  For

information contact ODA at 503-986-4701.



To add/remove your email address from this list, please go to:



http://listsmart.osl.state.or.us/mailman/listinfo/willamette-fcst



Pete Parsons

ODF Meteorologist
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20160711/84007b0c/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Silverton Hills Midday Forecast_Pete.doc
Type: application/msword
Size: 35840 bytes
Desc: Silverton Hills Midday Forecast_Pete.doc
URL: <https://omls.oregon.gov/pipermail/willamette-fcst/attachments/20160711/84007b0c/attachment.doc>